DIVERSITY OF CROCODYLIFORMES IN THE UPPER CRETACEOUS OF RINCÓN DE LOS SAUCES REGION (NORTHERN OF NEUQUÉN PROVINCE, PATAGONIA, ARGENTINA)

BARRIOS, FRANCISCO; FILIPPI, L.S.; PAULINA CARABAJAL, A.; CRUZADO CABALLERO, P.; ULLOA-GUAIQUIN, K.; GARCIA, S.; GONZALEZ DIONIS; BELLARDINI, F.

Salta

Jornada; Reunion de Comunicaciones de la Asociacion Paleontologica Argentina; 2023

APA IBIGEO IEBI UNSA IBIGEOP

The diversity of the Upper Cretaceous (Cenomanian to Maastrichtian) crocodyliforms in Argentinais represented by several families of notosuchians (Notosuchidae, Comahuesuchidae,Baurusuchidae, Peirosauridae), and basal mesoeucrocodylian taxa. Most species (such asNeuquensuchus universitas, Notosuchus terrestris, Comahuesuchus brachybuccalis,Cynodontosuchus rothi, Wargosuchus australis, Lomasuchus palpebrosus, Gasparinisuchuspeirosauroides, Bayomesasuchus hernandezi, Patagosuchus anieliensis, and Barrosasuchusneuquenianus) were recovered from the province of Neuquén (Patagonia, Argentina). From thenorthern of the province, at the Rincón de los Sauces region the species Pehuenchesuchus enderiand Kinesuchus overoi were described. Field work carried on in recent years in the region providednumerous crocodyliforms remains such as teeth, cranial and postcranial (osteoderms, vertebrae andappendicular) elements. Here, we provide a revision of the crocodyliforms remains in light of newfindings housed in the Museo Municipal Argentino Urquiza (MAU). Many of this fossil record isfrom the Cerro Overo-La Invernada, Puesto Hernández, Puesto Narambuena and Cañadon Río Secolocalities from levels of the Plottier (Upper Coniacian), Bajo de la Carpa (Santonian) and Anacleto(Lower Campanian) formations. In many cases the fossils are isolated and/or articulated fragments.Osteoderms are abundant with ornamentation based in subcircular pits, and a keel marked or not(e.g. MAU-Pv-LE-619, MAU-Pv-CO-692 to 695, 699 and 701). In second order in abundance areconical teeth crowns (caniniforms and molariforms) with denticulated carinae (e.g. MAU-Pv-CO-696 to 698, and 700). Postcranial remains comprise some complete vertebrae, neural arch andamphycelic vertebral body, both cervical, thoracic, lumbar, sacral and caudal (e.g. MAU-Pv-CO-584, 674). Appendicular elements include proximal and/or distal epiphysis (both humerus, femurand tibia) and pelvic bones (e.g. MAU-Pv-CO-584 cf. Kinesuchus and 676 to 678). As for thecranial remains, relatively complete skull roof and temporal elements were found (e.g. MAU-Pv-CO-632 and 686). Some mandibular fragments correspond to articular (as articular, surangular andangular bones; MAU-Pv-CO-690) and symphyseal (dentary and splenial bones; MAU-Pv-CO-583Kinesuchus holotype, and 680) regions. A relatively complete and articulated tail includingvertebrae and osteoderms was found as well (e.g. MAU-Pv-PH-437, MAU-Pv-LI-691). All thementioned crocodyliforms remains are assigned to Peirosauridae, except MAU-Pv-N-280 that couldbelong to a derived notosuchian. This shows the dominance of the peirosaurids in thepaleoenviroment of the region for the Upper Cretaceous (Coniacian to Santonian age mainly) incontrast with others notosuchians groups (such as notosuchids or baurusuchids).